High-speed Interconnect Platform Based On EtherCAT And Its Application In Wind Farm Substations

Traditional Ethernet is a mature technology,which has been widely used in industrial automation systems-However,the industry has raised higher real-time and reliability requirements for industrial control systems.Traditional Ethernet fieldbus technology can no longer meet the requirements.This paper is based on "MW-class wind turbine PLC Control system localization Project of XEMC" and "High-speed Interconnect Platform Design Based on EtherCAT".This paper aims to improve the real-time performance and reliability of the wind turbine PLC Control system.The paper takes the research of EtherCAT as the highlight and uses EtherCAT instead the traditional Ethernet.EtherCAT has improved the communication efficiency of the system communication networks,which achieves a real-time communication standard(lower than 1ms).Compared to traditional fieldbuses such as CAN,EtherCAT has realized the spans from milliseconds to microseconds of real-time performance.This topic is based on the EtherCAT protocol standard and has developed the EtherCAT interconnection platform,which provides a solution for the use of EtherCAT in the wind turbine PLC communication system-The main research contents of this paper are as follows:(1)EtherCAT protocol standard has been carried on the analysis,include EtherCAT operation principle,master station structure,slave station controller,state machine and application layer specification.The EtherCAT slave controller chips and microcontrollers have been compared and analyzed and development plan for EtherCAT slaves was written based on the EtherCAT protocol.The research difficulty of the paper was to realize the hardware and software system of the slave station,which involved the selection of the microprocessor chip,EtherCAT slave chip,etc.,and the optimization design of the hardware platform and software code.(2)The slave station development scheme has been designed based on FPGA and ET1200 and the slave station development scheme based on STM32 and LAN9252 successively.In this research,the soft core space of FPGA was not enough and the PCB design solution was difficult to wire and other issues.However,the solution of STM32 and LAN9252 exactly has been solved these problems.The paper ultimately has been determined the slave development program based on STM32 and LAN9252.And the paper has been developed EtherCAT slave development board in the Windows7.On this basis,this paper has been studied the application layer CoE protocol of the EtherCAT slave development board deeply.The CoE object dictionary has been designed,the CoE protocol was designed,the CoE mailbox protocol code and SDO communication service were optimized.The device description file ESI in a special XML has been designed based on the EtherCAT slave station interconnection platform.(3)The working principle of the TwinCAT3.1 has been studied,which was introduced by Beckhoff.The paper has been realized configuration of software.The TwinCAT3.1 development package has been used as the soft master station of the EtherCAT system and the design.The application platform of the slave station and TwinCAT3.1 have been established the EtherCAT master-slave communication environment architecture,and verified that establishment and communication of master-slave system was set up successfully and added object dictionary tests.The experimental results showed that the EtherCAT application platform has been achieveed normal communication and the master station correctly read the objects added by the slave station.(4)EtherCAT interconnection platform has been applied to the substation process level communication system.The DG/850-i609 development board and the EtherCAT interconnection slave platform,and the TwinCAT3.1 development kit has been built a GOOSE message transmission test environment based on the EtherCAT interconnection platform.The DG/850-i609 development board was acted as an intelligent electronic device(IED).The experiment tested the packet's waveform,packet loss rate,and real-time performance.The test results showed that EtherCAT real-time Ethernet communication for GOOSE messages was high reliablility and improveed the real-time performance.